Fan motor

• US 6,650,075 B2
• Filed: 07/02/2002
• Issued: 11/18/2003
• Est. Priority Date: 07/06/2001
• Status: Expired due to Fees

• Current Assignee: Japan Servo Co., Ltd. (Nidec Corporation)
• Original Assignee: Japan Servo Co., Ltd. (Nidec Corporation)
• Inventors: Kataoka, Koji, Otsuka, Motoi
• Primary Examiner(s): Nappi, Robert E.
• Assistant Examiner(s): MILLER, PATRICK L
• Application Number:
  US10/186,948
• Publication Number:
  US 20030006725A1
• Time in Patent Office: 504 Days
• Field of Search: 318/268, 318/138, 318/254, 318/439, 318/66, 318/68, 318/434, 318/490, 388/903
• US Class Current: 318/268
• CPC Class Codes: H02H 7/093 against increase beyond, or decrease below, a predetermined level of rotational speed centrifugal switches H01H35/10
• CPC Class Codes: H02P 29/02 Providing protection against overload without automatic interruption of supply protection against faults of stepper motors H02P8/36
• CPC Class Codes: H02P 6/28 Arrangements for controlling current H02P6/10 takes precedence
• CPC Class Codes: H02P 6/34 Modelling or simulation for control purposes

Abstract

A self-diagnosis device is provided with a fan motor having a stator on which a stator coil is mounted, a rotor having a permanent magnet and a fan, a Hall device for detecting magnetic pole position of the permanent magnet and a current control device for controlling rotation of the rotor by controlling current fed to the stator coil. The self-diagnosis device judges if the fan motor has exceeded its service life. Further, the self-diagnosis device interrupts the current fed to the stator coil when the rotational speed is higher than an allowable value, and restarts the current automatically to return the fan motor into normal operation when the rotational speed is not higher than the allowable value.

Claims

1. A fan motor comprising:

a stator on which a stator coil is mounted;

a rotor comprising a permanent magnet and a fan and being rotatably supported to oppose said stator coil;

a Hall device for detecting a magnetic pole position of said permanent magnet;

current control means for controlling rotation of said rotor by controlling current to be fed to said stator coil; and

self-diagnosis means for detecting the state of said fan motor, wherein an operation of said fan motor is controlled through said current control means based on a result from said self diagnosis means, wherein said self-diagnosis means includes

a current detection circuit for detecting an instantaneous current value in said stator coil,

current signal processing means for processing said instantaneous current value, and

memory means for processing and storing a steady state current value, said instantaneous current value being compared with said steady state current value for determining if said fan motor has exceeded a service life of said fan motor if a difference between said instantaneous current value and said steady state current value exceeds a predetermined value, wherein said current signal processing means further includes

zero timing generator means for receiving an output voltage from said Hall device and for generating a zero timing signal,

timing signal generator means for receiving said zero timing signal and for generating a timing signal,

sampling means for receiving said timing signal and for sampling said currently flowing current value,

A/D converter means for transforming said sampled currently flowing current value into a digital value, and

comparator means for comparing, at any time starting from receipt of said zero timing signal, said digital value of said instantaneous current value with a digital value of said steady state current value stored in said memory device, and said fan motor is determined to have exceeded the service life if the difference between said digital value of said instantaneous current value and said digital value of said steady state current value exceeds the predetermined value.

2. The fan motor according to claim 1, wherein said current signal processing means is operated by a program loaded in a microcomputer.

3. A fan motor comprising:

a stator on which a stator coil is mounted;

a rotor including a permanent magnet and a fan and being rotatably supported to oppose said stator coil;

a Hall device for detecting a magnetic pole position of said permanent magnet;

current control means for controlling rotation of said rotor by controlling current fed to said stator coil; and

self-diagnosis means for detecting the state of said fan motor, wherein an operation of said fan motor is controlled through said current control means based upon a result of said self-diagnosis means, wherein said self-diagnosis means further includes

reference voltage generator means for generating a predetermined reference voltage,

F/V converter means for transforming a rotational speed detected by use of an output voltage of said Hall device into a voltage proportional to said rotational speed, and

comparator means for comparing said reference voltage with said voltage proportional to said rotational speed, wherein said current fed to said stator coil is interrupted when said voltage proportional to said rotational speed is higher than said reference voltage, and said current fed to said stator coil is cut-off and automatically restarted to return said fan motor into normal operation when said voltage proportional to said rotational speed is less than or equal to said reference voltage.

4. The fan motor according to claim 3, wherein said self-diagnosis means is contained in a microcomputer, and is operated by a program loaded in said microcomputer.